The present invention relates to measuring devices and more particularly to an apparatus for measuring the linear dimensions of an article.
Various devices have heretofore been proposed and are presently available for measuring various dimensions of an article to determine if the article is within specifications or manufacturing tolerances. Some of these devices may also be used to mark or scribe stock material prior to performing fabrication steps. Among such devices are rulers, tape measurers, calipers, micrometers and height gauges. The prior devices may include mechanical and/or digital displays. Examples of prior proposals may be found in U.S. Pat. No. 4,229,883 entitled MEASURING INSTRUMENT WITH DIGITAL DISPLAY and issued on Oct. 28, 1980 to Kobashi; U.S. Pat. No. 4,255,861 entitled ELECTRICALLY DIGITAL DISPLAY MICROMETER and issued on Mar. 17, 1981 to Nakata et al; U.S. Pat. No. 4,399,613 entitled TWO-LEG VERNIER CALIPERS AND ITS MANUFACTURING METHOD and issued on Aug. 23, 1983 to Nishikata et al; and U.S. Pat. No. 4,399,617 entitled HEIGHT GAGE and issued on Aug. 23, 1983 to Yoshioka.
In many of the previous devices, a pinion engaging a rack or a photoelectrical reader riding along a glass scale having gradations thereon may be used for measuring displacement of a movable portion of the device and providing a digital readout. Examples of digital readouts may be found in U.S. Pat. No. 4,063,086 entitled SCALE READING APPARATUS and issued on Dec. 13, 1977 to Hirose; U.S. Pat. No. 4,096,384 entitled POSITION TRANSDUCER FOR MACHINE TOOLS AND MEASURING MACHINES and issued on June 20, 1978 to Sartorio et al; and U.S. Pat. No. 4.187,612 entitled HEIGHT GAGE and issued on Feb. 12, 1980 to Scott.
In many industries, it is important to accurately measure elongated sheet stock, templates, panels and the like which have linear dimensions on the order of 100 inches or more. Such articles, due to weight or size, must be supported while being measured. Precise measurement of such articles establishes the accuracy of the manufacturing process, permits the selection of accurately matching parts and allows quality control checking of articles supplied by subcontractors. Presently available measuring devices have not allowed the accurate, reliable and simple measurement of such articles. A need, therefore, exists for a reliable, easy to use and accurate apparatus which permits the measurement of articles having a relatively wide range of sizes or which must be supported other than by hand.